SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85f818fb3fad8f7a5eeb4c855c255fb817e60398785cb31b6e965d532033c735' 
  AND token = 'C5x+CXCwLDRpwzebwW0Ckpi0EWi4RhJGwfL47ZO2IlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}